The objectives of this work are 1) to determine the volume of the cytoplasm taken by the cytoplasmic matrix under different external osmotic environments, and how it affects the diffusional motion of proteins inside the cytoplasm and 2) determine the rate of intake of ligands during endocytosis. The cytoplasmic matrix is composed of a number of filamentous systems (microfilaments, intermediate filaments, microtubles, and the microtrabecular lattice). The use of the image analysis method that we developed demonstrated that the fractional volume of the cytoplasmic matrix is rather low (l6% - 21%). These values and the pore dimensions indicate that the cytoplasmic matrix slows down the diffusion of proteins to a great extent by transient binding. Refinement of the binding analysis showed that most of the matrix binding sites are free. The binding constants values point out that although the association-dissociation process can occur very quickly, most of the proteins are bound to the cytoplasmic matrix. We initiated the study of the effect of the external osmotic environment on the volume of the cytoplasmic matrix. The binding rate of a diffusing ligand to membrane receptors was calculated as a function of the internalization (endocytosis) rate. It was shown that when the internalization rate is relatively slow, the effect of the lateral distribution of the receptors on the ligand intake is not large compared with the situation where the internalization occurs instantly. The meaningfulness of this work lies in the fact that measuring the volume fraction of the cytoplasmic matrix can shed light on molecular transport through the cytoplasm. In addition, the amount of surface area associated with the cytoplasmic matrix which was estimated is important in understanding the role of hydrated water in the physiology of the cell. The result on the rate of intake of ligands by membrane receptors with different internalization conditions can shed light on different situations in endocytosis.